Aqueous siloxane bag lubricant for tire molding

ABSTRACT

A composition useful as a bag lubricant in tire manufacturing is disclosed which composition consists essentially of (A) 1 to 20 percent by weight of an alkylmethyl-siloxane fluid having from one to 20 carbon atoms in the alkyl group and at least 1000 cs. viscosity at 25* C., (B) 2 to 20 percent by weight of a material selected from the group consisting of (1) polyalkylene glycols having a molecular weight of at least 500 in which the alkylene oxide units are ethylene oxide units, propylene oxide units or combinations of ethylene oxide and propylene oxide units and (2) copolymers of alkylmethylsiloxanes and polyalkylene glycols in which the alkylene oxide units are ethylene oxide units, propylene oxide units or combinations of ethylene oxide and propylene oxide units, said copolymers having a viscosity of at least 200 cs. at 25*C. and containing from 5 to 50 percent by weight of the alkylmethylsiloxanes, (C) 25 to 50 percent by weight of mica of 75 to 600 mesh, (D) 0.1 to 5 percent by weight of a material selected from the group consisting of (1) finely divided magnesium silicate, (2) carboxymethyl cellulose and (3) carboxyethyl cellulose, (E) 0.1 to 5 percent by weight of lecithin, and (F) 15 to 55 percent by weight of water. Alternative formulation is a copolymer of an alkylmethyl siloxane and a polyalkylene glycol in lieu of components (A) and (B) in the preceding composition.

A 221 Filed:

United States Patent [1 1 Cekada,Jr.

in. 3,713,851 I 154] AQUEOUS SILOXANE BAG LUBRICANT FOR TIRE MOLDING[76] Inventor: Joseph Cek ada, Jr., 1827 Eastlawn,

[63] Continuation-impart of Ser. No. 148,899, June 1, 1971, which is acontinuation-in-part of Ser. No. 40,452, May 25, 1970, abandoned.

[52] U.S. C1. ..l06/38.22, 106/287 SB, ll7/5.l,

117/139, 252/28, 260/292 M, 260/37 SB, 264/338 51] Int. Cl..."..'......B28b 7/36 581 FieldofSearch ..l06/38.22, 38 27, 2,13,287;--

Primary Examiner-Lorenzo B. Hayes Attorney-Robert F. Fleming, Jr.

.[ 1 Jan. 30,1973

[57] 7 ABSTRACT A composition useful as a bag lubricant in tire manu-'facturing is disclosed which composition consists es-v sentially of (A)l to 20 percent by weight of an alkylmethyl-siloxane fluid having fromone to 20 carbon atoms in the alkylgroup and at least 1000 cs. viscosityat 25 C., (B) 2 to 20 percent by weight of a material selected from thegroup consisting of (1) polyalkylene glycols having a molecular weightof at least 500 in which the alkylene oxide units are ethylene oxideunits, propylene oxide units or combinations of ethylene oxide andpropylene oxide units and (2) copolymers of alkylinethylsiloxanes andpolyalkylene glycols in which the alkylene oxide units are ethyleneoxide units, propylene oxide Units or combinations of ethylene oxide andpropylene oxide units, said copolymers having a viscosity of at least200 cs. at 25C. and containing from 5 to 50 percent by weight of thealkylmethylsiloxanes, (C) 25 to 50 percent by weight of Inica of 75 to600 mesh, (D) 0.1 to 5 percent by weight of a material selected from thegroup consisting of (1) finely-divided magnesium silicate, (2)carboxymethyl cellulose and (3) carboxyethyl cellulose, (15.) '0.l'to 5percent by weight' of lecithin, and (F) 15 to 55 percent by weight ofwater. Alternative formulation is a copolymer of an alkylmethyl siloxaneand a polyalkylene glycol in lieu. of components (A) and (B) in thepreceding composition.

I0 Claims, Ni; Drawings AQUEOUS sILoxANE BAG LUBRICANT FOR TIRE MOLDINGThis application is a continuation-in-part of application, Ser. No.148,899 filed June 1, 1971, which application was a continuation-in-partof application, Ser No. 40,452 filed May 25, 1970, now abandoned.

The use of methylpolysiloxanes as release agents for tires and otherplastic articles is well known. In the manufacture of tires, themethylpolysiloxane fluid is sprayed on the mold for the release of thetire from the metal surface. In such applications dimethylpolysiloxanealone is an excellent release agent.

However, in the manufacture of the tire the actual shaping of the tireis caused by inflating a rubber bag inside the green tire carcass whichforces the tire into shape within the mold. Subsequently, the bag mustrelease cleanly from the inside of the vulcanized tire without formingdefects. The material used as a parting agent between the tire carcassand the bag is commonly called a bag or band-ply lubricant. Thisinvention is particularly designed to enhance the effectiveness of theselubricants.

ln applicants US. Pat. No. 3,532,624 there is disclosed and claimed aband-ply lubricant based on a solvent system. This composition hasobtained a wide commercial success in. the tire industry. However, withthe growing menace of air pollution it is often undesirable to employhydrocarbon solvents on a large scale. There is need for an aqueoussystem which will accomplish results equivalent to those of thecomposition in the aforesaid application. This invention offers such acomposition.

It is the object of the present invention to provide a band-plylubricant which'will improve bag life, give fewer tire rejects at loweroverall costs to the-manufacturer, which composition can be stored forlong periods of time without settling and which will avoid the necessityof using organic solvents.

This invention relates to a composition consisting of alkylene oxideunits are ethylene oxide units, propylene oxide units or combinations ofethylene oxide and propylene oxide units and (2) copolymers ofalkylmethylsiloxanes and polyalkylene glycols in which the alkyleneoxide units are ethylene oxide units, propylene oxide units orcombinations of ethylene oxide and propylene oxide units, saidcopolymers having a viscosity of at least 200 cs. at 25 C. andcontaining from 5 to 50 percent by weight of the alkylmethylsiloxane,(C) 25 to 50 percent by weight of mica of 75 to 600 mesh, (D) 0.1 to 5percent by weight of a material selected from the group consisting of 1)finely divided magnesium silicate, 2) carboxymethyl cellulose, and (3)carboxyethyl cellulose, (E) 0.1 to 5 percent by weight of lecithin, and(F) 15 to 55 percent by weight of water.

If desired, (B)(2) can be a mixture of an alkylene oxide and a copolymerof an alkylmethylsiloxane and alkylene oxide. 7

This invention also relates to a composition which consists essentiallyof (l) 3 to 40 percent by weight of a copolymer of analkylmethylsiloxane having from one to 20 carbon atoms in the alkylgroup, and a polyalkylene glycol in which the alkylene oxide units areethylene oxide units, propylene oxide units or combinations of ethyleneoxide and propylene oxide units, said copolymer having a viscosity of atleast 200 cs. at 25 C. and containing from 5 to percent by weight of thealkylmethylsiloxane, (II) 25 to 50 percent by weight of mica of 75 to600 mesh, (III) 0.1 to 5 percent by weight of a material selected fromthe group consisting of ('1) finely divided magnesium silicate, (2)carboxymethyl cellulose, and (3) carboxyethyl cellulose, (IV) 0.1 to 5percent by weight of lecithin, and (V) 15 to percent by weight of water.v

The siloxanesemployed herein are alkylmethyl-siloxanes which are fluidin nature and they must have a viscosity of at least 1000 cs. at 25 C.The upper limit of the viscosity is not critical so that it can rangeupwards of 10,000,000 cs. at 25 C. That is siloxane (A) could be anonflowing gum. The alkylmethylsiloxane can be a dimethylsiloxane, whichis preferred, or a siloxane of the unit formula RCH SiO in which R is analkyl group of from two to 20 carbon atoms such as an ethyl, isopropyl,butyl, octyl, dodecyl or C 11 group. These alkylmethylsiloxanes can behydroxyl endblocked or they can be endblocked with trihydrocarbon silylgroups. Also the alkylmethylsiloxane fluids can contain minor amounts ofRSiO and SiO units. These types of fluids are'well known in the art andno method for their preparation need be elucidated here.

Component (B) can be a polyalkylene glycol having a molecular weight ofat least 500. It can be, for example, polyethylene glycol, orpolypropylene glycol, or copolymersthereof. It is a combination of (A)and (B) which gives the proper lubricity to the bag. The initiatoremployed in the manufacture of the polyalkylene glycol is not criticaland if desired, the polyalkylene glycol can be endblocked with wellknown monovalent groups.

Component (B) can also be a copolymer of an alkylmethylsiloxane and apolyalkylene glycol in which the alkylene oxide units are ethylene orpropylene oxide or combinations of the two. These copolymers are wellknown materials of commerce and examples of the structure which areoperative herein can be found in numerous patents including US. Pat.Nos. 3,402,192, 2,846,458 and 3,057,901; Canadian Pat. 669,881; BelgianPats. 739,312 and 730,686; and French Pats. 1,259,241 and 1,353,070, allof which are hereby incorporated in this application by reference. Inthese copolymers the .alkylene oxide moiety can have hydroxyl ends orcan be endblocked with monovalent organic groups such as hydrocarbon,halohydrocarbon, carboxyl, SiR urethane or acyl groups. The polyalkyleneoxide moiety is attached to the siloxane moiety by a silicone-carbonbond, but the linking group between the polyalkylene oxide and thesiloxane moieties can be, for example, hydrocarbon or halohydrocarbon,or can contain ether, ester, sulfide or other linkages. These copolymerscan be linear, branched or cyclic in structure and they can have one ormore alkyleneoxide moiety attached may one silicon atom.

in which R and R are alkyl radicals of 1 to 20 carbon atoms,nisto 3,misOto 2,yis l to2,bis0oraninteger, c is an integer of at least 1, and Bis the group 'R'* (OR?),,OR in which R is the linking group as abovedefined, R is CH CH or H CH:

.-CH2 H- and R is a monovalent end group of any type such as shown aboveand d is such that the molecular weight of OR groups total at least1,000.

Ingredient (l) employed in this invention has the generic formula shownin the preceding paragraph and can have, for example, any ofthe'structures shown'in' any of the patents incorporated herein byreference, (I) has certain critical limitations not applicable to(B)(2). The viscosity of (I) must be atleast 200 cs. at 25 C. and thepercent by weight of thesiloxane must be in the range of from 5 to 50percent of the total weight of (l).

The finely divided magnesium silicate used herein is a standard articleof commerce. Any such material which causes thixotropy in water (i.e.the water is thickened under zero'shear but becomes fluid under shear)are operative herein. The magnesium silicate is sold in various formsand the term includes those magnesium silicates derived from clays suchas, for example, the saponites. The best types for use herein aremagnesium silicates which have tube and rod-like crystal structureswhich expand in the presence of water and which will contract -when the,water is removed. The term includes magnesium silicates containingaluminum in which the magnesium is in greater proportion than thealuminum. If desired, the magnesium silicate can be treated with variouswell known organic materials to increase the hydrophilic nature of thesilicate. 1 7

In lieu of the magnesium silicate there can be used carboxymethylcellulose or'carboxyethyl cellulose as the thickening agent. Thesematerials are well known and commercially available. The use ofcarboxymethyl cellulose is believed to result in a more stablecomposition and makes formulation of the composition easier.

The lecithin used herein is a naturally occurring material and can bederived from any source. One convenient source is from soya beans.

The compositions of this invention are characterized by great stabilityand they can be shipped and/or stored for long periods of time withoutsettling and then be i sprayed on the commercial apparatus employed inrubber plants and still give excellent release of the bag from the tire.This combination of properties means that the tire manufacturers can buya product readyrnade which operates successfully in their' plantswithout the necessity of having to formulate bag lubricants.

In addition to the above required ingredients the compositions of thisinvention can contain minor amounts of other fillers such as talc; rustinhibitors such as sodium nitrate; germicides such as formaldehyde andother ingredients such as coloring agents and antifreeze materials. I

The following ingredients used in the examples below are hereby defined.

VEEGUM (manufactured by R.T. Vanderbilt Company) is a magnesium silicatederived from saponite. It is an inorganic colloidal magnesium aluminumsilicate of the composition,

silicon dioxide 6 l .l% magnesium oxide [3.7% aluminum oxide 9.3%titanium dioxide 0.1% ferric oxide 0.9% calcium oxide 2.7%

sodium oxide 2.9% potassium oxide 0.3% carbon dioxide 1.8% and water ofcombination 7.2%

BENTONE LT is a product of National Lead Company and it is a magnesiumsilicate free of aluminum having a specific gravity of 1.9 and weighing16.5 pounds per gallon.

Dowicil 100 is a hexamethylenetetraamine-l-3- dichloropropane adductshown in US. Pat. No. 3,228,829. it is a germicide.

"The following examples are illustrative only and should not beconstrued as limiting the invention. In the examples Me is anabbreviation for the methyl radical.

The compositions of this invention can-be put prior to admixing theother components therewith.

All parts and percents referred to herein are by weight and allviscosities measured at 25 C. unless otherwise specified.

EXAMPLE 1 This example shows the stability of the compositions tosettling.

0.4 pounds of VEEGUM was dispersed in 7.6 pounds of water and then mixedwith 5.72 pounds of a 35 percent aqueous. emulsion of a 100,000 cs.dimethylpolysiloxane fluid, 5.6 pounds of a silicone-polyalkylene oxidecopolymer of the average formula and having a viscosity of 1200 cs. at25 C., 0.8 pounds of soya lecithin and 4.68 pounds of additional water.The mixing was carried out on a Cowles dissolver and 15.2 pounds of mica(325 mesh) was blended in the total composition and was passed through acolloid mill set at 30 mils.

The stability of the composition was checked for compaction of the micaby centrifuging 5 minutes at 2000 rpm. The mica had not settled out. Thecomposition was then placed on a truck which was then driven 500 miles.The stability was excellent. The formulation in percent by weight was 5%dimethylpolysiloxane 100,000 cs.

14% silicone-polyalkylene oxide copolymer 1% VEEGUM 2% lecithin 38% mica40% water.

EXAMPLE 2 Using the procedure of Example 1, the following compositionwas prepared percent by weight.

5.0% of a polydimethylsiloxane of 100,000 cs.

viscosity 12.0% of the silicone-polyalkylene oxide copolymer of Example1 v 41.0% of 325 mesh mica 1.0% soya lecithin 0.5% VEEGUM 40.5% water.

The composition showed excellent stability while being sprayed through aconventional band-ply lubricant system in a tire factory, It gaveexcellent release of the tires from the bag.

EXAMPLE 3 Using the procedure of Example 1 the following formulation wasmade in percent by weight.

I 5.0% of the siloxane of Example 1 12.0% of OH:(O CzHi) 03115) 0H of2,600 mol weight 02114) (0 aHo) on 112(0 03H!) (0 0 H) OH 1.0% soyalecithin 0.5% VEEGUM 41.0% mica 325 mesh 0.3% of 30% formaldehydesolution 40.2% water.

This formulation showed excellent three months storage.

EXAMPLE 4 The following formulationwas prepared in percent by weightusing the method of Example 1.

stability after 5 .0% of the siloxane of Example 1 12.0% of thepolyalkylene glycol of Example 3 41.0% mica (325 mesh) 1 .0% soyalecithin 1.0% VEEGUM 0.1% Dowicil 100 39.92 water This formulationshowed excellent stability and was sprayed on the bags for molding tiresin a tire factory. 60

Excellent release was obtained and the tires were without defect.

EXAMPLE 5 Good stability was obtained withthe following formulation.

5.0% of the siloxane of Example 1 0.7% BENTONE LT 12.0% of thepolyalkylene glycol'of Example 3 1.0% soya lecithin 41.0% mica (325mesh) 5 40.3% water The ingredients were mixed on a Cowles mixer.

EXAMPLE 6 [This example shows the operativeness of a high viscositysiloxane-polyalkylene oxide'copolymer in place of the mixture 'ofsiloxane and polyalkylene ox ides of Examples 1 to 5.

Good stability was obtained from the following formulation in percent byweight. 23 percent of a 7 13,571 c's. viscosity copolymer of the formulaMe; S i(O S 1Mez)4s (O S iMe)aoO S iMe;

41% mica (325 mesh) 50 mol percent ethylmethylsiloxane EXAMPLE 8Equivalent results are obtained when the following siloxane-alkyleneoxide copolymers are used in place of the siloxane-alkylene oxidecopolymers of the preceding examples.

i 7 1 MezSiO s10 S1Me;

( CzHOnOH EXAMPLE 9 A band-ply lubricant composition was prepared whichconsisted essentially of 14.3 percent of the dimethylpolysiloxaneemulsion of Example 1 12.0 percent of the polyalkylene glycol of Example3, 41.0 percent of mica 325 mesh), 0.3 percent of carboxymethylcellulose, 1.0 percent of soya lecithin, 0.1 percent of about 325 mesh,(D) about 05 percent of magnesium Dowicil 100, and 31.3 percent ofwater. This composiymethyl cellulose. Then the water,dimethylpolysiloxane emulsion, lecithin, Dowicil and mica were added andmixed in, in the order just stated. After all the ingredients had beenmixed thoroughly, the composition was given one pass through a colloidmill at a 0.025 inch setting. This composition was easy to formulate,exhibited excellent stability, andgave excellent release when used as aband-ply lubricant. The composition had an initial viscosity of 52,000cs. Two days after preparation it had a viscosity of 44,000 cs., threedays after, it had a viscosity of 36,000 es. and 18 days after it had aviscosity of 35,000 cs. The composition was centrifuged for 40 minutesat 2000 r.p.m.s and no compaction of the mica was observed.

EXAMPLE l iNhen carboxymethyl cellulose is substituted for the magnesiumsilicate (VEEGUM) in the composition of Example 6, substantiallyidentical results are obtained.

EXAMPLE} 1 B 2 to 20 percent by weight of a material selected from thegroup consisting of l) polyalkylene glycols having a molecular weight ofat least 500 in which the alkylene oxide units are ethylene oxide units,propylene oxide units or combinations of ethylene oxide and propyleneoxide units and (2) copolymers of alkylrriethyl-siloxanes having fromone to 20'carbon atoms in the alkylgroups and polyalkylene glycols inwhich the alkylene oxide units are ethylene oxide units, propylene oxideunits or combinations .of ethylene oxide and propylene oxide units, saidcopolymers having ,a viscosity of at least 200 cs. at 25 C. andcontaining from to 50 percent by weight of the alkylmethylsiloxane, a

C. 25 to 50 percent by weight of mesh,

D. 0.1 to 5 percent by weight of a material selected from the groupconsisting of (H finely dividedmagnesium silicate, (2) carboxymethylcellulose, and (3) carboxyethyl cellulose,

E. 0.1 to 5 percent by weight of lecithin, and

F. to 55'percent'by weight of water.

2. A composition as defined in claim 1 wherein (A) is adimethylsiloxane, and (B) is a polyalkylene glycol.

3. A composition as defined in claim 2 which consists essentially of (Al about 5 percent of a dimethylsiloxane having a viscosity of about100,000 cs., (B) about 12 percent of a polyalkylene glycol in which thealkylene oxide. units are a combination of ethylene oxide and propyleneoxide units, (C) about '41 percent of mica of mica of 75 to 600silicate, (E) about 1 percent of soya lecithin, and (F) about 40.5percent of water. 7

4. A composition as defined in claim 2 which consists essentially of (A)about 5 percent of a dimethylsiloxane having a viscosity of about100,000 cs., (B) about 12 percent of a polyalkylene glycol in which thealkylene oxide units are a combination of ethylene oxide and propyleneoxide units, (C) about 41 percent of mica of about 325 mesh, (D) about0.3 percent of carboxymethyl cellulose, (E) about 1 percent of soyalecithin, and (F) about 40.7 percent of water.

5. A composition as defined in claim 1 wherein (A) is a dimethylsiloxaneand (B) is a copolymer of a dimethylsiloxane and a polyalkylene glycol.

6. A composition as defined in claim 5 which consists essentially of (A)about 5 percent of a dimethylsiloxane having a viscosity of about100,000 cs., (B) about 12 percent of a copolymer of the average formula(cmnsio'iicimisioin} Fra's'iolfs flciiiil h a)a l( sM i luICIQSiOhSKCH(C)about 41 percent of mica of about 325 mesh, (D) about 0.3 percent ofcarboxymethylcellulose, (E) about 1 percent of soya lecithin,and (F)about 40.7 percent water.

8. A composition consisting essentially of 1.3 to 40 percent by weightof a copolymer of an alkylmethyl-siloxane having from one to 20 carbonatoms in the alkyl group, and a polyalkylene glycol in which thealkylene oxide ,units are ethylene oxide units, propylene oxide units orcombinations of ethylene oxide and propylene oxide units, said copolymerhaving a viscosity of atleast 200 cs. at 25 C. and'containing from 5 to50 percent by weight of the alkylmethylsiloxane,

ll. 25 to 50 percent by weight of mica of to 600 mesh,

III. 0.1 to 5 percent by weight of a material selected from the groupconsisting of (l) finely divided magnesium silicate, (2)carboxymethylcellulose, and (3) carboxyethyl cellulose,

IV. 0.1 to 5 percent by weight of lecithin, and

V. 15 to 55 percent by weight of water,

9.. A composition as defined in claim 8 which consists essentially of(I) about 23 percent of a copolymer of theaverage formula v v Hmsu 0suommml o s i cliili uo swam ll. about 41 percent of mica of about 325mesh, [I]. about 1 percent of carboxymethyl cellulose,

lV. about 1 percent of soya lecithin, and

V. about 34 percent of water.

1. A composition consisting essentially of A. 1 to 20 percent by weightof an alkylmethylsiloxane fluid having from one to 20 carbon atoms inthe alkyl group and at least 1,000 cs. viscosity at 25* C., B. 2 to 20percent by weight of a material selected from the group consisting of(1) polyalkylene glycols having a molecular weight of at least 500 inwhich the alkylene oxide units are ethylene oxide units, propylene oxideunits or combinations of ethylene oxide and propylene oxide units and(2) copolymers of alkylmethyl-siloxanes having from one to 20 carbonatoms in the alkyl groups and polyalkylene glycols in which the alkyleneoxide units are ethylene oxide units, propylene oxide units orcombinations of ethylene oxide and propylene oxide units, saidcopolymers having a viscosity of at least 200 cs. at 25* C. andcontaining from 5 to 50 percent by weight of the alkylmethylsiloxane, C.25 to 50 percent by weight of mica of 75 to 600 mesh, D. 0.1 to 5percent by weight of a material selected from the group consisting of(1) finely divided magnesium silicate, (2) carboxymethyl cellulose, and(3) carboxyethyl cellulose, E. 0.1 to 5 percent by weight of lecithin,and F. 15 to 55 percent by weight of water.
 2. A composition as definedin claim 1 wherein (A) is a dimethylsiloxane, and (B) is a polyalkyleneglycol.
 3. A composition as defined in claim 2 which consistsessentially of (A) about 5 percent of a dimethylsiloxane having aviscosity of about 100,000 cs., (B) about 12 percent of a polyalkyleneglycol in which the alkylene oxide units are a combination of ethyleneoxide and propylene oxide units, (C) about 41 percent of mica of about325 mesh, (D) about 0.5 percent of magnesium silicate, (E) about 1percent of soya lecithin, and (F) about 40.5 percent of water.
 4. Acomposition as defined in claim 2 which consists essentially of (A)about 5 percent of a dimethylsiloxane having a viscosity of about100,000 cs., (B) about 12 percent of a polyalkylene glycol in which thealkylene oxide units are a combination of ethylene oxide and propyleneoxide units, (C) about 41 percent of mica of about 325 mesh, (D) about0.3 percent of carboxymethyl cellulose, (E) about 1 percent of soyalecithin, and (F) about 40.7 percent of water.
 5. A composition asdefined in claim 1 wherein (A) is a dimethylsiloxane and (B) is acopolymer of a dimethylsiloxane and a polyalkylene glycol.
 6. Acomposition as defined in claim 5 which consists essentially of (A)about 5 percent of a dimethylsiloxane having a viscosity of about100,000 cs., (B) about 12 percent of a copolymer of the average formulaC. about 41 percent of mica of about 325 mesh, (D) about 0.5 percent ofmagnesium silicate, (E) about 1 percent of soya lecithin, and (F) about40.5 percent of water.
 7. A composition as defined in claim 5 whichconsists essentially of (A) about 5 percent of a dimethylsiloxane havinga viscosity of about 100,000 cs., (B) about 12 percent of a copolymer ofthe average formula (C) about 41 percent of mica of about 325 mesh, (D)about 0.3 percent of carboxymethylcellulose, (E) about 1 percent of soyalecithin, and (F) about 40.7 percent water.
 8. A composition consistingessentially of I. 3 to 40 percent by weight of a copolymer of analkylmethyl-siloxane having from one to 20 carbon atoms in the alkylgroup, and a polyalkylene glycol in which the alkylene oxide units areethylene oxide units, propylene oxide units or combinations of ethyleneoxide and propylene oxide units, said copolymer having a viscosity of atleast 200 cs. at 25* C. and containing from 5 to 50 percent by weight ofthe alkylmethylsiloxane, II. 25 to 50 percent by weight of mica of 75 to600 mesh, III. 0.1 to 5 percent by weight of a material selected fromthe group consisting of (1) finely divided magnesium silicate, (2)carboxymethyl cellulose, and (3) carboxyethyl cellulose, IV. 0.1 to 5percent by weight of lecithin, and V. 15 to 55 percent by weight ofwater.
 9. A composition as defined in claim 8 which consists essentiallyof (I) about 23 percent of a copolymer of the average formula II. about41 percent of mica of about 325 mesh, III. about 1 percent of magnesiumsilicate, IV. about 1 percent of soya lecithin, and V. about 34 percentof water.